An Air New Zealand B787 Dreamliner flight to Sydney has turned back to Auckland Airport because of a smell of burning aboard the plane – for the second time in a week.

It was the same flight, NZ103 to Sydney.

In the latest incident, crew reported an odour of electrical burning on the flight.

Fairfax New Zealand reported a “full-scale emergency service response” with six fire trucks was launched for the NZ103 flight, which landed safely and without incident and taxied back to the gate.

An Air New Zealand spokeswoman said the flight “returned shortly after take-off as a precaution after an unusual smell was detected in the cockpit. It landed without incident around 9.45am”.

The aircraft was removed from service to be inspected by engineers, with passengers moved to an alternative service, she said.

The same NZ103 flight was forced to return to the gate on Tuesday morning, when passengers were said to have looked out the window and noticed an engine was emitting smoke.

A “strange, acrid smell” filled the cabin, reports from New Zealand said.

Fairfax in New Zealand quoted TVNZ reporter Andrea Vance, a passenger on the NZ103 flight, saying she saw smoke coming from the right engine on Tuesday.

In a statement on Wednesday, Air New Zealand said engineers had undertaken extensive testing of the 787 aircraft and determined it was “normal vapour”.

“We have also consulted the engine manufacturer Rolls Royce which confirms this phenomenon occurs more in certain conditions and the vapour is a normal operation for this type of engine,” Air New Zealand’s chief flight operations and safety officer Captain David Morgan said.

“The safety of our customers, employees and aircraft is of utmost importance to Air New Zealand. We appreciate our customers bringing this to the attention of our crew so we could properly investigate the cause.”

The earlier incident occurred four days after an Air New Zealand domestic flight made an emergency landing at Auckland Airport after suffering engine problems.

In that incident, flight NZ8117 from Auckland to Palmerston North ran into trouble shortly after take-off and the pilot elected to shut down one of the engines as a precaution, before landing without incident.